Add an option to disable horizontal scrolling

libinput always has horizontal scrolling enabled and punts the decision when
to scroll horizontally to the toolkit/widget. This is the better approach, but
while we have a stack that's not ready for that, and in the X case likely
never will be fully ready provide an option to disable horizontal scrolling.
This option doesn't really disable horizontal scrolling, it merely discards
any horizontal scroll delta. libinput will still think it's scrolling.
https://bugs.freedesktop.org/show_bug.cgi?id=91589Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>